High-Sn fraction GeSn quantum dots for Si-based light source at 1.55 μm

Abstract

The preparation of GeSn quantum dots (QDs) facilitates the solution of Si-based light source for communication. The GeSn QDs with a uniform size of 5 nm embedded in amorphous GeSn were synthesized by low temperature annealing on amorphous GeSn strips intersected with Sn strips. The Sn fraction in GeSn QDs is much higher than that in original amorphous GeSn matrix. A novel growth mechanism related to Sn diffusion induced nucleation and the strain limitation effect was proposed. The direct bandgap of ∼0.8 eV extracted from room-temperature photoluminescence and absorption spectra is larger than the theoretical prediction of 0.41 eV in bulk GeSn with Sn fraction of 13.6%.